The black DB-SH1M Stereo Headphone Amplifier made by RDL is a dual channel headphone amplifier with balanced/unbalanced left and right inputs. Each input accepts operating levels between -20 dBV and +20 dBu. Prior to mounting the module, there are two recessed switches on the rear enclosure that are set up. One switch is for setting the input sensitivity and the other is the mode switch.
The mode switch selects between stereo and mono operation. In the mono position, the left input is used to drive both output channels. When the module is used in a monaural system, only the left channel input must be wired. The front panel level control is a long life potentiometer controlling matched VCAs. Audio does not pass through this control.
The output amplifiers deliver more than 50 mW into either high or low impedance headphones. Module operation is from a 24 VDC ground referenced power supply. This amplifier is designed to fit Decora style products and American electrical boxes.